Network Function Virtualisation: Infrastructure Overview

1. Network Function Virtualisation -
Infrastructure Overview
Neelima Sharma

2. The content of this presentation is taken from the ETSI
NFV specifications and from various presentations
available on internet

3. What is covered…
 NFV Infrastructure – Overview
 NFV Infrastructure – Architecture
 NFV Infrastructure – NFVI and Cloud
Computing
 NFV Infrastructure – Domain architecture and
associated interfaces
 NFV Infrastructure – Compute Domain
 NFV Infrastructure – Hypervisor Domain
 NFV Infrastructure – Network Domain
 NFV Infrastructure – Challenges

4. NFV Infrastructure - Overview
 Below figure illustrate the section related to the Infrastructure

5. NFV Infrastructure - Overview
 NFV Infrastructure architecture is primarily concerned
 Compute Domain
 HyperVisor Domain
 Infrastructure Domain
 Hypervisor Domain provides
 Sufficient abstraction of the hardware for the portability of the Software
appliances
 Provide compute domain resources to the S/W appliances VM machines
 Provides management interfaces to the orchestration and management
system

6. NFV Infrastructure – Reference Architecture Framework

7. NFV Infrastructure – Architectural Principles of VNF
 System engineering approach of defining components as functional
block and their interconnection
 After network functions are virtualised

8. NFV Infrastructure – Architectural Principles of VNF
 Behavior of functional block is determined by
 Static transfer function of the functional blocks
 Dynamic state of the functional blocks
 Inputs it received in its interface
 Virtualization resulted in the following
 Division of functional block between a host function and VNF
 Creation of new container interface between the host function and the
VNF it is hosting
 Division of the interface between the two network functions which are
now virtualized between infrastructure interface and a virtualized
interface
 Relationship between VNF and host
 VNF is a configuration of the host function
 VNF is an abstract view of the host function when configured by VNF

9. NFV Infrastructure – Architectural Principles of VNF
 NFV architecture is defined using the following entities
 Host functions with their associated offered container interfaces and
associated infrastructure interfaces
 VNF with their associated used container interfaces and virtualized
interfaces

10. NFV Infrastructure – Management and Orchestration of
VNF
 Network functions have an interface ( North bound interface) to a
management and orchestration function

11. NFV Infrastructure – NFVI and Cloud Computing
 Five essentials characteristics of cloud services
 On demand self service
 Broad network access
 Resource pooling
 Rapid elasticity
 Measured service
 Service models impacting NFVI
 SaaS
VNF’s are software applications on cloud
VNF’s are executed according to a private cloud model
 Example is VNFaaS

12. NFV Infrastructure – NFVI and Cloud Computing
 PaaS
Service model consistent with deployment by network operators of services
 VNPaaS is a use case
 IaaS
Capability provided is the provisioning of compute, storage and
communication resources for the application to run
 Good use case is NFVIaaS

13. NFV Infrastructure – Domain Architecture and Associated
Interfaces

14. NFV Infrastructure – Domain Architecture and Associated
Interfaces
 VNF can be decomposed and made up from sub-parts which are
themselves VNF which are interconnected by infrastructure
 VNF’s can automatically request for management and orchestration
 Network interfaces must be decomposed between the infrastructure
protocols and the VNF protocols
 Infrastructure network is completely abstracted by the network infrastructure
container interface
 NFV infrastructure, applications and MANO are fully interoperable with the
existing OSS/BSS and carrier networks
 Below attached excel provides the details of the interfaces

15. NFV Infrastructure – Compute Domain
 Role of the Compute domain is to provide the interface to the network
infrastructure domain but does not support network connectivity
 Principal elements of the compute domain
 CPU
 Network Interface Controller (NIC)
 Storage
 Server
 Chasis
 Remote management
 Functional description of the compute domain needs to reference the
speed of execution

16. NFV Infrastructure – Compute Domain
 Primary characteristics of storage are :
 Latency in accessing a specific state held in storage
 Size of the storage
 Volatility or persistence of the storage
 Scope of Compute node includes
 CPU with storage
 Hardware for encryption and decryption
 Packet switching
 Accelerated packet forwarding

17. NFV Infrastructure – Hypervisor Domain
 Mediates the resources of the computer domain to the virtual
machines which includes :
 CPU
 NIC and so on …

18. NFV Infrastructure – Hypervisor Domain
 Forthcoming hardware improve the performance of VM’s which
includes
 multicore processors supporting multiple independent parallel threads of
execution
 system-on-chip processors that integrate multiple cores, DRAM
interfaces, network interfaces, storage,interfaces and hardware
acceleration for security, multicore processing, networking, storage and
application acceleration.
 specific CPU enhancements/instructions to control memory allocation
and direct access on I/O devices to VM memory allocations
 PCI-e bus enhancements, notably SR-IOV

19. NFV Infrastructure – Hypervisor Domain
 Specific features of hypervisor support for high performance NFV
VMs include
 exclusive allocation of whole CPU cores to VMs
 direct memory mapped polled drivers for VMs to directly access the
physical NICs using user mode instructions requiring no ‘context
switching’
 direct memory mapped polled drivers for interVM communications again
using user mode instructions requiring no ‘context switching
 vSwitch implementation as a high performance VM again using direct
memory mapping and user mode instructions requiring no ‘context
switching’

20. NFV Infrastructure – Hypervisor Domain Architecture
 Below figure illustrates the hypervisor domain architecture

21. NFV Infrastructure – Network Domain Reference point
Architecture
 Below figure illustrates the network domain reference point
architecture in the NFVI

22. NFV Infrastructure – Network Infrastructure Domain
 Roles of network domains includes :
 Communication channel between the VNFC’s of a distributed VNF
 Communication channel between different VNFs
 Communication channel between VNFs and their orchestration and
management
 Communication channel between components of the NFVI and their
orchestration and management
 Means of remote deployment of VNFCs
 Means of interconnection with the existing carrier network

23. NFV Infrastructure – Network Infrastructure Domain
 Essential elements needed for providing the connectivity with
domain:
 An infrastructure addressing scheme with address allocation and
management
 A routing process which can relate infrastructure addresses to routes
through the infrastructure network topology
 A bandwidth allocation process
 A set of OAM processes to verify reliability, availability and integrity of
connectivity services
 Requirement for bandwidth aspects requires :
 Permanently allocated, fully guaranteed bandwidth
 Respecting prioritization markings of the packet
 Guaranteed minimal latency variation

24. NFV Infrastructure – Network Infrastructure Domain
 Requirement for infrastructure network and VNF protocols to work
together
 Common Header
MAC header associated with NIC should be understood by both
 Transparent encapsulation
Carry the packet from the VNFC as a transparent payload and must add a
completely new header for transport by the infrastructure network
 Address binding
Mac addresses presented to the VNFC must be bound to infrastructure
network addresses

25. NFV Infrastructure – Challenges in Performance
 General recommendations to apply to network SW design
 SW requiring high performance should be partitioned in independent
modules running in different threads
 Modules should have independent memory structures in order to avoid
OS deadlocks
 Modules should communicate each other in pipeline structures,
minimising the use of the OS as an intermediate step
 OS interruptions should be reduced, if possible, to zero, due to its high
consumption of CPU cycles
 The use of OS network stacks should be avoided
 Network cards and other peripherals should communicate directly with
the modules through memory

26. NFV Infrastructure – Challenges in Interconnection of VNF